1. Technical Field
This invention relates generally to a system and method of transferring a wireless communication device from a first network to a second network, and more specifically to a system and method for rapidly and seamlessly transitioning a communication connection between a wireless wide area network and a wireless local area network having a different radio access technology.
2. Background Art
In recent years, mobile telephones have enjoyed explosive growth in popularity. Once a luxury for only a few, today millions of people use mobile telephones to stay connected with friends, family, and coworkers. Coupled with the rise in popularity of mobile telephones has been an improvement in wireless communications networks. Older, analog systems have given way to new digital technologies and high capacity communication networks. Communication systems like Code Duplex Multiple Access (CDMA) and Global Systems for Mobile Devices (GSM) offer mobile telephone users reliable voice connections around the world.
In addition to voice communication, many mobile phones today are capable of exchanging packet data. For instance, phones capable of working in General Packet Radio Service (GPRS) systems are capable of exchanging packets of data between the mobile phone and a wireless network. While many wireless wide area networks offer switched packet data service, the data transfer rates can be slow. Additionally, some service providers charge additional fees for switched packet data service, because it consumes network resources that might otherwise be used for voice calls.
Technological advances in wireless Local Area Network (LAN) technology offer an alternative to wireless wide area networks. The cost of Wireless LAN (WLAN) equipment has become so affordable that many businesses, including hotels, coffee shops and airports, offer “hot spots” within which a wireless device may connect with a WLAN, such as a private Intranet or a public network like the Internet or World Wide Web. These WLANs often offer significantly higher data transfer rates and are generally provided by businesses at no charge to the end user to entice patronage. The presence of these WLANs gives users alternative paths with which to transfer data, and even voice (where using Voice Over IP (VOIP) technology, for example). Indeed, some mobile devices provide for switching between wireless wide area networks and WLANs to take advantage of the higher data speeds and lower costs when a WLAN is present.
The problem with such devices is that they must execute a complicated and time-consuming handoff procedure when transitioning from one wireless network to the next. For example, when a user moves from an IP Multimedia Subsystem (IMS) LAN network to a GSM wide area network, the device must scan the area to detect the wide area network and then determine (generally by downloading large amounts of data) what kind of network it is, what protocol it uses, how to connect to it, what channels to use, when to connect and, so forth. Each of these steps consumes both time and device processing power. Consequently, when the process takes too long, voice and data connections may be delayed or interrupted.
There is thus a need for an improved system and method for rapidly and efficiently facilitating the handoff of a wireless device from a wireless network of one type to a wireless network of another type.